1. Field of the Invention
This invention is generally directed to heating devices and more specifically to water heaters of the type which are utilized to supply warm water to divers working in cold water areas. The invention is directed to a portable high efficiency heat exchanger wherein the water or other fluid to be heated is initially heated while being conveyed through the firebox of the heat exchanger. The fluid is thereafter directed into a heat exchange chamber which surrounds the firebox and is indirectly heated by energy passing through the walls of the firebox. The water or other fluid is further heated in heat exchange relationship with the exhaust gases from the firebox as the fluid is conveyed through passages which define a second indirect heat exchange chamber which is in surrounding relationship with respect to the exhaust gas flue of the firebox.
The heat exchanger of the present invention is designed to provide a generally continuous source of warm water which, in a preferred embodiment, is supplied directly to a diver working in cold deep sea, lake or gulf areas and includes one or more pumps by way of which water is conveyed through the heating system.
The system of the present invention also provides for user safety by automatically regulating the fluid temperature by controlling the rate at which the fluid passes through the heat exchanger and by automatically terminating fluid supply and shutting off the heat exchanger should fluid temperature rise above a predetermined level. In some instances, fresh liquid may be mixed with the heated fluid in the event the water rises above the predetermined temperature.
2. History of the Related Art
Over the years there have been a number of innovations directed to supplying heated water to divers who work in cold waters, often at water temperatures which are extremely hazardous to the diver's safety. Further, it has been found that, by providing warm or natural body temperature water to the suits of underwater divers, the divers are able to complete tasks more proficiently.
In U.S. Pat. No. 3,391,686 to Wiswell, Jr. a wet suit heating apparatus is disclosed wherein a source of fresh water supply, such as lake, gulf or sea water, is introduced into a heat exchange element where it is heated by steam tubes. The steam is created by utilizing a small portable boiler heated by kerosene, oil or similar fuel.
In U.S. Pat. No. 3,572,314 another type of heated diving suit is disclosed wherein the source of fluid to be heated is passed through a heat exchanger in direct contact with the exterior jacket of a firebox in which a fuel nozzle is located to burn oil or other combustible fuels. Once the fluid has been heated it passes through appropriate valves to the diving suit.
Another type of water heating system for divers is disclosed in U.S. Pat. No. 3,762,392 to Long. The Long heater utilizes a closed circuit system for continuously maintaining the water temperature. The heated water is mixed with a suitable quantity of unheated water so as to deliver a source of constant temperature water to a diver.
Further examples of portable water or other fluid heating units are disclosed in U.S. Pat. No. 4,390,304 to Sloan and U.S. Pat. No. 4,505,254 to the inventor of the present invention. In the Sloan device, the source of fluid is drawn when necessary and passed through an unspecified heating element after which the water is mixed with fresh water to a desired temperature and then supplied to a diving suit. In applicant's prior patent, a special type of water heater is disclosed for increasing the heat exchange efficiency of the heating system to thereby reduce fuel costs and provide for an increase in heater efficiency. More specifically, the heating unit includes a firebox having a plurality of exhaust channels extending therefrom in the form of heat exchange tubes. The tubes pass through a surrounding water jacket and thereby provide a source of heat exchange to the incoming water surrounding the firebox. In this manner, water is heated not only by contact with the sides of the firebox but is heated by contact with portions of the flue or tubes which extend upwardly through the heating unit. As with other prior art systems the heated water is conveyed through a safety control valve system before being directed to a diver's suit.
Some additional examples of prior art heaters which may be portable and which are not specifically designed for use in providing warm water to divers are disclosed in U.S. Pat. No. 4,480,631 to Kristensen, U.S. Pat. No. 4,766,883 to Cameron et al, U.S. Pat. No. 4,830,710 to Thompson, and U.S. Pat. No. 4,981,112 to Adams et al.